Very short period grating printing combining UV interferential exposure and mechanical strain

- Optical limitations of an holographic bench have been exceeded by the way of mechanical post-treatment
- The photoresist deposition and thermal post-process have been developed to amorphous PET film substrates
- 1D and 2D Gratings on PET substrate have been stretched reaching permanent plastic deformation
- 2 D gratings with period below 200 nm have been demonstrated over cm2 areas

A new original and innovative method is proposed to exceed the minimum period achievable with holographic lithography by employing the mechanical property of the substrate and using properties of plastic deformation of thin film polymer. It is demonstrated that the grating's period can be reduced from 250 nm to almost 180 nm keeping an acceptable profile without any defect due to mechanical strain, showing good adhesion and mechanical stability of the grating.

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